Internal-combustion engine



R. P. GRIEVE.

INTERNAL COMBUSTION ENGINE.

APPLICATION FILED SEPT-9,1919.

Patented June 29, 1920.

- UNITED STATES 3101mm) PALMER vs, or BOSTON, MASSACHUSETTS.

PATENT OFFICE.

INTERNAL-COMBUSTION ENGINE.

To all whom it may concern Be it known that I, RICHAR P. GRIEVE, a citizen of the UnitedStates, and a resident of Chelsea, Boston, in the county of Suffolk and State of Massachusetts, have invented a new and Improved Internal Combustion Engine, of which the following is a full,

clear, and exact description.

This invention relates to new and useful improvements in internal combustion engines, and it pertains more particularly to a piston construction. therefor.

Insome types of internal combustion engines, there are two pistons, which are move able relatively to the cylinder and to each other, and it is the primary object of the present invention to improve the construc tion of pistons in these types of engines.

It is a further object of the invention to construct the internal combustion engine pistons in such a mannerthat one of said pistons is adapted to be protected by the other piston.

Engines of the two-cycle typehave been constructed in the aforementioned manner, but it has been found that the upper or super-piston owing to its exposure to the continuous action of the burnt gases, has a tendency to superheat, and when in this condition acts to pre-ignite the fuel charge and produce a detrimental effect upon the efli ciency of the engine:

It is a further object of the invention to construct a super-piston in such a manner that its radiating surface is greatly increased contiguous to the walls of the cylinder in order that the same may be more effectively cooled. 1

In addition to the advantageous results obtained by this increase of radiating surface, the skirt formed on the upper end of the main piston serves to strengthen and stiffen the same, thus serving'to effectively prevent any distortion or warping incident to high temperatures which frequently occur. It is to be understood that the specific length of this skirt may be varied as desired without departing from the spirit of the invention.

With the above and other objects in View, reference is had to the accompanying drawings in which- Figure 1 is a vertical sectional view of an internal combustion engine cylinder showing the pistons thereof in elevation;

I Specification of Letters Patent. Patented 1111 1 29, 19,2(1

Application filed September 9, 1919. Serial No. 322,651.

Fig. 2 is a similar View showing the pistons in vertical section, and I Fig. 3 is a sectional view taken on the line 3-3 of Fig. 2."

Referring more specifically to the drawings, the reference character 5. designates the internal combustion engine cylinder, and

said cylinder 5 is provided with an intake port 6, and an exhaust opening 7, which is controlled by meansof a valve& In the present instance, the device comprises a main piston 9 and a supplementary or subpiston 10, which latter is provided with a 9 has its upper end reduced, as at 15, and f the upper endof said reduced-portion is provided with an annular, angular wall 16. The sub-piston 10 is provided with an annular depending flange or skirt 20, the upper portion of said skirt being thickened as at Q 21, to provide an angular wall 22 adapted to coincide with the annular, angular wall 16 of the main piston 9 when its reduced portion 15 is received therein. The depending flange 20 is provided around its periphery with a plurality of grooves 26, and said grooves 26 are adapted to communicate, near the upper end of the sub-piston 10, with an annular groove 27, transverse grooves 28 passing through the thickened portion 21 of the annular flange or skirt 20, and forming means establishing communication between the interior of the skirt 20 and the groove 27, and thence with the interior of the cylinder 5 in the compression space thereof.

As best seen in Fig. 3, it will be noted that the grooves 26 and 28 are equi-distantly spaced about the peripheral face of the subpi'ston 10 in order that the gas be uniformly distributed within the cylinder with greater facility.

The operation of the device is as follows:

Upon the power stroke of the piston, both the main piston '9 and,the sub-piston 10 move downwardly into the cylinder 5 under the influence of the expanding gases contained in the cylinder. After the two pistons 9 and 10 havetraveled through a portion of the cylinder in unison, the movement of the sub-piston 10 is retarded by a suitable mechanism (not shown), thus allowing the main piston 9 to separate therefrom. As further movement of the piston 9 takes place, the shoulder thereof opens the take port 6 for the purpose of taking in a fresh charge ofexplosive mixture.

As the main piston 9 starts upwardly on the compression stroke, the fresh charge taken into the cylinder is compressed between said pistons from; whence it passes around to the upper face of the sub-piston 10 by means of the by-passes formed by the grooves 26 and 28, the lastrmentioned bypass permitting all of the gasesbetween the two pistons moving to the upper face of the sub-piston 10, as the, reduced portion 15 of the main piston passes into the depending annular flange or skirt 20, a The two pistons 9 and- 10 now move upwardly ofvthe cylinder until the compression of the explosive charge is complete, whereupon said compressed charge is ignited and the 'a-bove described operation repeated;

Having thus described the inventiomwhat is claimed: ascnew is:

1-. In a an internal combustion engine,- a cylinder, a piston having a reduced end and slidably mounted in said cylinder, a "second piston mounted between the first-mentioned piston and one end of said cylinder, an annular flange integral with the'second-mention'ed piston and adapted to receive the reduced end of the first-mentioned piston and provided with a'series of circumferentially arranged by-passes adapted to establish; communication between the interior of said"; annular flange and the exterior of the pi s-i ton, and means for controlling the relative 40 movement of said pistons. v

2. In an internal combustion engine, a cylinder having an enlarged upper portion, a piston movable withrespect to said cylinder, a second piston movable relatively to said cylinder and said first-mentioned piston, and an annular flange carried by the second-mentionedpiston and adapted to engage a reduced end of the first-mentioned piston, said annular flange havingradially arranged passages passing therethrough adapted to establish communication between the i nteriorof said annularflange V and the enlarged portion of said cylinder, v

substantially as described;

RICHARD PALMER G i EvE, V Witnesses: I OARLETON F. MEnoHANT', I

BLANCHE HEWITT. 

